The pandemic caused by the new coronavirus has generated a situation unprecedented in recent history, with several million infected and hundreds of thousands of deaths. This disease is easily transmissible by air. Although a high percentage of cases present mild clinical presentation, approximately 15% of patients present moderate to severe cases and 5% require critical care, with respiratory assistance and a high risk of mortality. No effective therapies for the treatment or prevention of SARS.CoV2 have been identified yet. Preliminary evidence indicates that passive immunotherapy with convalescent plasma could alter the clinical course of this infection in a favorable manner. This strategy, even if confirmed as successful, requires voluntary donation by patients who have recovered, not all of whom are eligible as donors, since the antibody response varies in magnitude in different patients. This adaptive stage II/III study aims to analyze the efficacy and safety of passive immunotherapy by administering a purified Fab fraction of equine hyperimmune serum (INM005) generated from antigenic stimulation with the SARS-CoV2 RBD protein, with the objective of neutralizing the interaction of SARS-CoV-2 with its cellular receptor, thus preventing the multiplication of the virus. The safety of this type of equine hyperimmune sera has already been demonstrated in previous and ongoing protocols with a biologically equivalent product against the E. Coli shiga toxin to treat patients with Hemolytic Uremic Syndrome (CT-INM004-01 and CT-INM004-02). In the present study, eligible patients will with moderate to severe symptoms of COVID-19 that require hospitalization will receive two 4 mg/kg doses of INM005, two days apart, with the aim of improving the clinical course of COVID-19 28 days after the start of treatment with the study drug.